Uniform tension attachment for knitting machines



Aug. 15, 1950 2,518,615

UNIFORM TENSION ATTACHMENT FOR KNITTING MACHINES D. M. HARMAN Filed July 26, 1948 David M. Ha rman INVENTOR.

I BY My Patented Aug. 15, 1950 UNITED STATES PATENT OFFICE I UNIFORM TENSION ATTACHll/IENT FOR KNITTING MACHINES 9 Claims. 1

This invention comprises novel and useful improvements in a uniform tension attachment for knitting machines and more specifically pertains to a device for imparting a variable or adjustable but uniform tension to a plurality of threads which are continuously supplied to the knitting heads of various types of knitting machines.

The principal object of this invention is to provide an apparatus wherein the various threads supplied to the knitting instrumentalities of a knitting machine may be tensioned uniformly to improve the knittin characteristics of the machine, and wherein the tension imparted to a plurality of such threads may be simultaneously and uniformly varied as desired.

A further object of the invention is to provide an attachment, in conformity with the foregoing objects, which may be readily applied to existing knitting machines at a minimum cost and with ease and without diiliculty.

Yet another object of the invention is to provide an apparatus as set forth in the above objects which shall be lightweight and of inexpensive construction, dependable in its use, and which will give invariable uniform tensioning to the plurality of threads with which the device is associated, throughout the life of the device.

An important feature of the invention resides in the provision of a thread tensioning assembly which may be applied to existing snapper bars of knitting machines as a replacement for the conventional snappers customarily provided thereon, and which when so applied will automatically perform the functions of the conventional snappers, without however any variation in the tensioning in the individual threads passing through the device.

A further important feature of the invention resides in the provision of a tensioning mechanism wherein the plurality of threads are passed over a plurality of curved surfaces for imparting a frictional drag or tensioning of the thread, without the formation of restricted apertures which may be clogged or worn by the sizing with which the threads are customarily provided or by the friction and attrition of the threads passing therethrough.

These, together with various ancillary features and objects of the invention, which will later become apparent as the following description proceeds, are attained by this device, a preferred embodiment of which has been illustrated by way of example only in the accompanying drawings, wherein:

Figure 1 is a perspective view of a tensioning device constructed in accordance with the principles of this invention, fragments of a snapper shaft and of a stationary bar together with several threads tensioned by the device being shown associated therewith;

Figure 2 is a vertical transverse sectional view taken substantially upon the plane of the section line 2-2 of Figure 1 and showing one manner of passing a thread through the device for imparting the requisite tension to the thread when the knitting machine is used in a splicing operation;

Figure 3 is a view similar to Figure 2 but illustrating a conventional form of snapper with which knitting machines have been heretofore provided, and showing a thread passing through the snapper, for illustrating a known type of construction whose disadvantages this apparatus is designed to'overcome;

Figure 4 is a view similar to Figure 2 but showing another arrangement for passing a thread through thetensioning device for imparting the requisite tension thereto when knitting the leg of a stocking on a knitting machine; and

Figure 5 is a view similar to Figure 2 but showing a still further manner of passing a thread through the tensioning device for imparting a still further tensioning action, commensurate with that necessary for forming welts on stockings or the like.

This invention relates generally to similar subject matter set forth in the prior patent of Schletter No. 2,031,430, patented February 18, 1936. However the present invention differs fundamentally from the Schletter device in that a much improved and simplified bracket means are provided for holding the tensioning rods, wherein a much simplified and superior means for adjusting the tension of the threads is provided.

Referring now more specifically to the accompanying drawings, wherein like numerals designate similar parts throughout the various views, attention is directed primarily to Figure 3 wherein the numeral i0 designates the well known oscillating snapper bar or snapper rod forming a conventional part of various knitting machines such as the Reading full fashioned knitting machine, while 12 indicates a stationary bar forming a part of such machine and which is utilized in practising the principles of the present invention.

Figure 3 discloses a conventional snapper indicated generally by the numeral It, with which this machine is customarily provided, it being well known that it is necessary to provide one snapper for each thread indicated by the numeral l6, which is supplied to the knitting head of the machine. The conventional snapper I4, includes a hub portion [8, having an arcuate cutout portion 20 designed to embrace and seat upon the snapper bar "I, to be retained thereon as by a set screw 22, whereby the snapper is caused to oscillate upon oscillatory movement of the snapper bar I0.

The snapper further includes a pair of divergent arms 24 and 26, the former having an angulated end portion 28, within which is frictionally or otherwise seated an eyelet or bushing 30 of a restricted size, and whose upper end extends above the upper surface of the angulated portion 28 for a purpose to be later set forth. The arm 26 is likewise provided with an'eyelet or bushing 32 as shown in Figure 3 and it is customary for the thread Hi to :be threaded and to pass from its spool or spindle, through the eyelet 32, over the top of the upwardly extending end of the eyelet 30 and down through the same, and from thence as indicated by the arrow 34 in Figure 3, to the knitting instrumentalities.

It should be here noted that the eyelets 36 and 32 are extremely small in size and are generally of a hard vitreous material such as porcelain or the like.

Secured to an angulated extremity 360i the arm 26 of the snapper as by a screw 38, is a leaf spring member 48 which overlies the flange 28 and the eyelet 30 therein and extending thereabove, which leaf spring is provided with an enlarged aperture 42 which loosely surrounds the extending end of the eyelet 30. The resiliency of the spring 40 is such that the spring normally rests snugly against the upper surface of the angulated portion 28, in a manner surrounding the eyelet, whereby the thread [6 threaded through the snapper will be frictionally engaged below asurface of the spring 40 and the upper portion of the angulated portion 28 in advance of the thread's passage through the eyelet, whereby the spring and arm of the snapper impose a frictional resistance upon the passage of the thread through the eyelets.

As is well known, in the operation of a knitting machine, various mechanisms not shown impart an oscillating motion to the snappers which motion is synchronized with the operation of the knitting head, whereby at each loop gathering operation, predetermined tension is applied to the passage of the thread through the tensioned device or snappers in order to maintain a controlled tension upon the thread during its formation of the loops in the knitting operation. Obviously, it is desired that this tension shall be uniform throughout the entire knitting operation of an article such as a stocking and any failure to maintain such uniform tension upon a thread will result in various non-uniform or irregular knitting in the article, with attendant defects well known to those skilled in the art. Further, if a uniform tension is not maintained among the plurality of threads passing through the various snappers to a given knitting head, numerous other defects are apparent in the finished prodnot.

However, the conventional type of snapper above described has been heretofore unsatisfactory and unreliable in obtaining uniform tensions between the various threads of a knitting head and even upon the same thread throughout the knitting of an article for the following reasons. First, it has proved to be a practical impossibility to obtain a plurality of springs 40 of absolutely uniform spring characteristics throughout their length, to mount these springs by the screws 38 upon the flanges 36 of the snappers in such a manner as to cause this clamping action upon the springs to provide an exactly equal spring tensioning action upon the thread I6 as the latter passes between the spring and the flange 28, and finally the slightest blow is frequently sufllcient to change the effective tension of a spring upon its thread. In addition to these mechanical defects. which are inherent in this type of construction for tensioning the threads,

it has been found that the threads I 6 which are conventionally coated with sizing or the like during the knitting operation, tend to scrape off the sizing and deposit the same against the adjacent surfaces of the angulated portion 28, the snapper sprin 49 and the upper edge of the eyelet 3ii, as the thread is drawn thereover. This sizing piles up, and when hardened constitutes a serious obstruction to the passage of the thread, thus varying the tension or drag of the device; and in addition builds up and prevents the spring 48 from pressing downwardly upon the flange 28 with an invariable tension. Finally, the threads employed possess abrasive properties, which despite the hardness of the vitreous eyelet 30, produce appreciable cuts or grooves in the lip or upper rim of the same, further varying the degree of tension imparted to the thread by the device.

The present device is particularly intended to produce an invariable but adjustable tension upon any one thread, and simultaneously upon all of the threads of a knitting head, and which will not be appreciably aifected by wear or other conditions throughout the life of the device.

For this purpose, a plurality of parallel tension bars are mounted upon brackets secured to the snapper shaft it for oscillation thereby; and the various knitting threads it; are threaded through the series of tension rods in various ways to impose a variable frictional drag or tension upon the same, whereby all of the threads may be uniformly tensioned.

A convenient mechanism for carrying out this concept consists of a. plurality of brackets, which may conveniently consist of end brackets 44 and 45, together with one or more intermediate brackets 48. These brackets are all of identical construction as regard contour, shape, material and dimensions. Each has a recessed portion 50, similar to the portion 29 of the snapper l4, and is provided with a fastening screw 52 similar to the set screw 22, whereby the brackets may be clamped in various angular dispositions upon: the snapper shaft or rod 10 in the same manner as the snappers (4. As shown in Figure 2, each of the brackets has an arcuately cut-away recessed portion 54 which is adapted to receive the stationary bar 12, in one position of the oscillatory movement of the tensioning device, as shown in Figures 1 and 2. The intermediate supports 48 are provided with a plurality of suitably spaced laterally extending bores, while the end supports it and are provided with aligned blind holes or bores, whereby a plurality of tension rods may be carried and clamped thereby into a unitary assembly.

Obviously, any suitable number of these tension rods may be provided, and they may be arranged between the supports in various ways to function and produce the effect set forth hereinafter. Thus, a lower or inner set of bars 56, E8, 68 and 82 may be provided, together with an. upper or outer set of similar tension rods or bars 54, 66, 68 and 18. As will readily be understood by examining Figure 1, it will be seen that when the threads I 6 are threaded through the series of tension bars, that a certain frictional drag will be imparted to the thread as when drawn through the bars of the tensioning device by the operatien of the knitting heads. Obviously, as the tension bar assembly is oscillated with the shaft ID, in the direction of the arrow i2, the various portions of the threads extending between adjacent bars will have their angular relation varied, thereby changing and varying the tension or frictional drag imparted to the threads by the device as the threads are drawn therethrough.

It will further be understood that by varying the angular engagement of the support brackets 44, 45 and 48 upon the snapper rod or bar [9, that the initial tension of all of the threads may be varied; and that the range of variable tensioning resistances imparted to the threads will likewise be varied uniformly for the plurality of threads passing through the device.

It is contemplated that the requisite particular tension required for a set of threads for performing a particular knitting operation may be attained by selecting an appropriate arrangement for passing the threads through the series of tension bars, and Figures 2, 4 and 5 show satisfactory arrangement for different types of knitting motions. Thus, in Figure 2, the threads are shown as passing over the upper tension bar 64, under the upper bar 66, over the upper bar 68, and thence over the upper bar $2, whereby the sole tensioning effect imparted to the thread arises from the deflections or angular inclinations of the thread as it enters the tensioning device at B4, and as it is deflected downward under the bar 66 and upward to the bar 68. Of course, in one oscillating position of the device, the recess 54 envelopes the stationary bar [2, whereby the latter as shown in Figure 2, will further depress the thread IS and tension the same in addition to the above described tensioning action. The stationary bar l2 thus imparts an additional tension to the thread which is synchronized with the operation of the knitting instrumentalities to thus imply a periodic increase in tension to the knitting heads for tightening the loops and the like. This arrangement is satisfactory for the operation of splicing.

The arrangement illustrated in Figure 4 will be found sufficient usually for providing the necessary tensioning force for the operation of legging. Here, the thread [6 is passed over the tension rods 56, 58, 60 and 10, and under the rods e4, 66, and 68, as well as under the stationary part I 2. As will be readily seen, a different degree of tensioning action is imparted to the thread during its passage through the tensioning bars in this arrangement.

Finally, as shown in Figure 5, the thread l6 may be passed over the tension rods 56, 58, 68, 62 and under the stationary bar l2. This arrangement is satisfactory for performing welting operations.

The various tension rods, when inserted through the bores of the intermediate supports or brackets 48, and into the blind bores of the brackets 44 and 46, may be rigidly retained therein as by means of set screws or the like 14 which extend through these brackets and engage the tension rods, thus uniting rods and brackets into a rigid assembly.

Obviously, other arrangements for securing the bars to their supporting brackets, and for adjusting the supporting brackets upon the snapper rod l0 may be employed.

From the foregoing, the manner of constructing and operating the device together with its obvious advantages will be readily understood and further explanation is believed to be unnecessary.

However, since numerous modifications and changes will readily occur to those skilled in the art after a consideration of the foregoing specification and accompanying drawings, is not desired to limit the invention to the exact construction shown and described, but all suitable invention, what is I claimed as new is:

1. A thread tensioning device for knitting machines having an oscillatory tensioning shaft and a relatively stationary bar parallel thereto, comprising a pair of brackets fixed on said shaft, a plurality of parallel tensioning bars carried by said brackets for oscillation therewith, said bars being disposed at varying distances from the axis of said shaft and being relatively movable with respect to said relatively stationary bar.

2. The combination of claim 1 wherein said bars are disposed in pairs, said pairs being unequally spaced from said axis and having bars spaced at unequal distances from said axis.

A thread tensioning device for knitting machines having an oscillatory tensioning shaft and a stationary bar parallel thereto, comprising a pair of brackets fixed on said shaft, a plurality of parallel tensioning bars carried by said brackets for oscillation therewith, said bars being disposed at varying distances from the axis of said shaft, said brackets having recesses for receiving said stationary bar, said brackets and tensioning bars being so positioned radially of said shaft that the oscillation of said brackets and bars will cause the stationary bar to be received in said recesses, whereby said stationary bar will engage and additionally tension threads carried by said tensioning bars.

4. The combination of claim 1 wherein said bars are received in bores in said brackets.

5. The combination of claim 4 including means for retaining said bars in said bores.

6. A thread tensioning device for knitting machines having an oscillatory tensioning shaft and a stationary bar parallel thereto, comprising coextensive parallel end and intermediate brackets adjustably mounted on said shaft, aligned bores in said brackets, a series of tensioning rods in said bores parallel to said shaft, said rods being disposed in pairs unevenly spaced from said shaft, said rods being adapted to receive a plurality of knitting threads entrained through said series of rods in side by side relation for uniformly tensioning said threads during passage through said series, means for fastening said rods in said bores, said stationary bar additionally tensioning said threads upon oscillation of said shaft.

'7. The combination of claim 6 wherein said brackets have arcuate recesses for detachably receiving said shaft and means for radially adjustably securing said brackets to said shaft.

8. The combination of claim 6 wherein said brackets have cut-away portions between pairs of rods for receiving said stationary bar.

9. The combination of claim 8 wherein said brackets have arcuate recesses for detachably receiving said shaft and means for radially adjustably securing said brackets to said shaft.

DAVID M. HARMAN.

REFERENCES CITED The following references are of record in th file of this patent: 

